For purposes of control and accuracy, it is desirable that a less than maximum draw force be perceived by an archer when the bowstring has been pulled taut. To that end, a number of bow designs utilize cams suspended between the bow limbs to control the relative motion between the bow string and the bow limbs such that maximum pull is reached at an intermediate draw position. Such designs are described in U.S. Pat. Nos. 3,981,290, 4,287,867, and 5,388,569. In the U.S. Pat. No. '569 patent, a cam assembly is disposed adjacent the interconnection of the outer and power limbs, and interconnected to the riser using a pair of corresponding pulleys.
A more specific compound bow design designed and manufactured by Oneida Labs of Fulton, N.Y., is illustrated in FIGS. 2 and 3. The bow 10A includes a riser portion 12A having a pair of outer limbs 54, each limb being hingably attached to the distal end of a respective power limb 38. The opposite or proximal end of each power limb 38 is attached to the end of the riser portion 12A. A drawstring 74 extends between the distal ends of the outer limbs 54.
More specifically, a single cam 156 is centrally mounted to an axle disposed between a pair of mounted parallel extension plates 140, 144 at the top and bottom of the riser portion 12A, the plates being directly attached by fasteners thereto. A pair of cables 110, 120 extend from each cam 156, one of the cables 110 being interconnected with the outer limb 54 to rotate the mounted cam in response to pulling of the drawstring 74. As the cam 156 rotates past its knockover point, the tension in the drawstring as perceived by the archer is significantly reduced, thereby allowing a level of accuracy and control at the time most needed.
The remaining cable 120 interconnects each cam 156 with each flexible power limb 38 to bias and return the cam to its original prefiring position after the tension of the drawstring 74 has been removed, using the hinged arrangement between the outer limb 54 and the power limb.
In the described bow design, the plates 140, 144 must extend a considerable distance in order to allow the mounted cam 156 to successfully rotate. In addition, because the cam 156 is centrally disposed between the two plates 140, 144, an intermediate yoke 130 is required to allow interconnection of the first cable 110 from the internal grooves of the cam 156 over the edges of the outer limb 54. Similarly, a clevis block 160 is also required to interconnect the remaining cam cable 120 to the power limb 38.
Each of the above components introduce a level of structural complexity, as well as add weight to the above described bow. For example, the use of the intermediate yoke constrains the sizing of the bow, preventing the manufacture of bows for younger users. It is a perceived desire in the industry to be able to construct and manufacture a compound bow including a cam assembly for lessening the draw force, but which optimizes weight, size and manufacturability.